Sterilization microwave heating

Studies of microwave-assisted pasteurization and sterilization have been motivated by the fast and effective microwave heating of maity foods containing water or salts. Rosenberg and Bog (1987) reviewed it in detail. 

Dry heat is used to sterihze and depyrogenate components and drug products. The definition of dry heat sterilization is 170 °C for at least 2 hours and a depyrogenation cycle at 250 °C for more than 30 minutes. Typical equipment includes tunnel sterilizers (force convection, infrared, fiame) and microwave sterilizers. An important aspect is the need to ensure air supply is filtered through HEPA filters. Biological indicators such as Bacillus subtilis can be used to gauge the performance of sterilization. 

PDCB was prepared by suspending cut-up unpeeled potatoes (100 g L ) and carrots (10 g L ) in purified water and heated to boiling in a microwave oven for 5-10 min. Dextrose (d-(- -)-glucose) was added (30 g L ). The medium was sterilized by autoclaving for 20 min at 121 °C and then decanting off the broth. The broth is clear to slightly opalescent and yellowish in colour. No pH adjustment was made. 

Polyethersulfone compositions, (1), having high heat tolerance, good impact resistance, and Tg s greater than 235°C were prepared by Brunelle [1] and used as trays in steam autoclave sterilization units and as microwave cookware. Johnson [2] determined that the impact strength of this composition was greater than the commercially available polyethersulfone, RADEL . 

For instance, if ampules of aqueous products were to be sterilized in a hot air oven, the mechanisms of microbial inactivation would still be by coagulation of intracellular proteins. However, heat transfer from hot air is much slower than heat transfer from steam, which is why this is not seen as a practical process. Microwave irradiation could be an alternative means of sterilizing aqueous pharmaceutical products utilizing the same antimicrobial mechanisms as steam certainly there is evidence that microwave killing patterns are mainly due to heat transfer with very little direct energy being absorbed from the microwaves. 

Heating a container with a loosened cap or lid poses a significant risk. Microwave ovens can heat material (e.g., solidified agar) so quickly that, even though container lids may be loosened to accommodate expansion, the lid can seat upward against the threads and containers can explode. Screw-caps must be removed from containers being microwaved. If the sterility of the contents must be preserved, screw-caps may be replaced with cotton or foam plugs. 

The polysulfones resin family offers many desirable properties for cookware products in both commercial and consumer markets. In addition to those mentioned above, other noteworthy features are resistance to hot greases and detergent solntions and microwave transparency. Coffee carafes, steam-heated food service trays, and a variety of plastic parts used in honsehold appliances are a few examples of these uses. Sulfone polymers are also used in antomated dairy processing components as an alternative to stainless steel becanse of their clarity, hydrolytic stability, and resistance to sterilization. 

Kel-F can be sterilized with y-rays, ethylene oxide, or heat and is only vulnerable to tetrahydro-furan (THF) and a few halogenated solvents. It is microwave transparent. Common uses of KEL-F are connectors, valves, cells, and lab on valve (LOV) platforms. 

Like Kel-F, PEEK can be sterilized with yr ys, ethylene oxide, or heat. PEEK is commonly used in tubing, connectors, cells, and valves. It is also very used in microwave vessels in combination with Teflon. The Teflon inner vessel provides chemical resistance, whereas the external vessel made of PEEK provides mechanical robustness. 

Drying ovens should never be used to re-melt solidified agar media because too much water will evaporate from the medium. Re-autoclaving media for a complete sterilization cycle will also degrade heat-sensitive nutrients in the medium. Rather, solidified media can be melted by placement in a boiling water bath or a microwave, the later performed with hand mixing every few minutes. 

In either case, the time-temperature measurement within the moving food particulates is difficult, and consequently assuring commercial sterility without overprocessing is not a straightforward matter. In this p ier, we will discuss how thermally produced compoimds can be used as chemical markers of sterility in ohmic heating and microwave sterilization. 

The reported chemical markers are useful markers of sterility, which is an important quality index in shelf-stable foods. The use of the markers to map lethality distribution in particulate foods has been demonstrated. The markers can be used for validating and optimizing new thermal processing technologies such as ohmic heating and microwave sterilization. 

Paper/foil and paper/film laminations are used for many appHcations including candy wrappers, microwave packaging, ice cream carton lids, and reflective building insulation. Flexible laminations are multilayered composites, with each each component providing special properties. Examples include snack food bags, aseptic containers sterilized by radiation or heat, meat packages, solar screen laminations, and flexible air ducts. 

Microwave sterilization is a new method and it plays a significarrt role in synthesis (Honda et al., 1998 Sasaki et al., 1998a). The sterilization is brought about by microwave dielectric heating effect. The efficiency of a microwave sterilizer was... 

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